Method for producing wood chips



Nov. 3, 1964 K. c. LOGAN ETAL 3,155,130

METHOD FOR PRQDUCING woon CHIPS Fi1ed Feb. 15, 1963 '7 sheetsr-sneet 1 INVENTORS Kenneth C. aga/z ATTORNEY Nov. 3, 1964 K. c. LOGAN ETAL METHOD Foa PRonucING woon cx-xPs 7 Sheets-Sheet 2 Filed Feb. 15, 1963 INVENTOR Kenneth C Logon O/o e/o 0'// @XMIM 5.

ATTORNEY NOV- 3, 1964 K. c. LOGAN ETAL 3,155,130

METHOD FOR PRODUCING WOOD CHIPS Filed Feb. 15, 1963 7 Sheets-Sheet 3 INVENTOR /fznneth C. Logan Mya@ lef/1 ATTORNEY N0V 3 1964 K. c. LOGAN ETAL. 3,155,130`v METHOD FOR PRODUCING WOOD CHIPS Filed Feb. l5, 1963 '7 Sheets-Sheet 4 INVENTOR /fmnzh C Logan Madam ATTORNEY Nov. 3, 1964 K. c. LOGAN ETAL METHOD FOR PRoDucING woon CHIPS '7 Sheets-Sheet 5 Filed Feb. l5, 1963 N M \\-l wwf a P f QMNQ In? u m N mfg KO 1x L.. Aw

ATTORNEY Nov. 3, 1964 K. c. LOGAN ETAL 3,155,130

METHOD FORPRODUCING WOOD CHIPS Filed Feb. 15, 196s 7 sheets-sneer e ATTORNEY Nov. 3, 1964 K. c. LOGAN ETAL 3,155,130

METHOD FOR PRODUCING WOOD CHIPS Filed Feb. l5, 1963 7 Sheets-Sheet 7 INVENTOR /fmneh C4 aga/2 O/a' Sepa/f ATTORNEY United States Patent O ice 3,155,125@ v METHGD EGR FRGBUCING WGE @IaIFS Kenneth E. Logan and Gia Sepall, Quebec CityuQnehec, Canada, assignors to Angie Paper Products, Limited, Quebec City, Quebec, Canada Fiied Feb. 15, 1963, Ser. No. 258,695 Claims. (Cl. 144-326) This invention relates to a method for producing wood chips for pulping and for particle board production and the like. This application is a continuation-in-part of application Serial No. 87,966, filed February 8, 1961 and now abandoned.

It has long been recognized that the conventional wood chipper as employed for the production of chips used in the manufacture of pulp damages the wood fibers and thus results in lowered pulp quality. This is due to the fact that the standard chipping operation crushes or compresses the Wood bers when severing a chip angularly of the grain direction. The situation was discussed at length in an article entitled The Eect of Chipping on the Suitability of Wood for Sulphite Pulping by H. Green and F. H. Yorston, which appeared in Pulp and Paper Magazine of Canada, Convention Issue, 1940. This article suggests that undamaged chips may be prepared by sawing up logs into discs of chip length and, subsequently, splitting up the discs with a knife. However, the operation of sawing up logs into discs produces large quantities of sawdust, which is undesirable for economic reasons and such an operation is extremely extravagant of labor and equipment.

Despite widespread recognition of the need for producing substantially undamaged wood chips and the knowledge that such substantially undamaged wood chips would result in a much superior type of pulp, no commercially acceptable or practical manner of producing such chips has heretofore been proposed.

It is a general object of this invention to provide a method for producing wood chips of improved characteristics for pulping in an eiiicient, economical, and practical manner.

It has been found that chips produced in standard chipping machines have been compressed in the grain direction substantially greater than 0.060 inch per inch and usually in excess of 0.080 inch per inch and that this excessive compression that results in lower pulp quality. If the compression in producing chips is never more than 0.060 inch per inch, and preferably not more than 0.010 to 0.040 inch per inch, the quality of pulp produced therefrom is uniformly of much higher quality.

Applicants have found that, if the chip is severed from the surface of the log by producing a cut in the log hav ing a rst portion extending parallel to the grain of the wood in the log and at least one other portion extending angularly to the grain of the wood in the log, these portions of the cut being substantially simultaneously performed, and the direction of the cut being at an angle of 100 to 70 to the grain of the Wood, the resulting chip possesses the desired improved characteristics.

Applicants have also found that it is desirable that the angular portions of the cut be at an angle of 95 to 175 to the lirst portion of the cut.

The invention will be described with reference to the accompanying drawings, in which,

BSE Patented Nov. 3, 1964 FIGURE 1 is a side elevation of a machine for producing chips in accordance with the invention,

FIGURE 2 is an end elevation of the machine shown in FIGURE 1,

FIGURE 3 is an enlarged sectional end elevation of the knife assembly and holder and mounting therefor,

FIGURE 4 is a perspective View of the knife assembly and holder,

FIGURE 5 is a pian view of the front knife member,

FIGURE 6 is an end elevation of the front knife member,

FIGURE 7 is a plan view of the main knife,

FIGURE 8 is a plan view'of a chip produced in accordance with the present invention,

FIGURE 9 is a side elevation of the chip shown in' FIGURE 8,

FIGURE 10 is an end elevation in FIGURE 8,

FIGURE 11 is an end elevation of an alternative form of knife arrangement,

FIGURE 12 is a side elevation' of the knife arrangement shown in FIGURE 11,

FIGURE 13 is an end elevation of another form of knife arrangement,

FIGURE 14 is a perspective View of an alternative form of knife assembly,

FIGURE 15 is a bottom profile of the knives shown in FIGURE 14 When cutting tangential to the log,

FIGURE 16 is a perspective view of an alternative form of knife,

FIGURE 17 is a bottom profile of an arrangement of knives as shown in FIGURE 16,

FIGURE 18 is a perspective view of an alternative form of knife,

FIGURE 19 is a bottom profile of an arrangement of knives as shown in FIGURE 18,

FIGURE 20 is a perspective view of an alternative form of knife,

FIGURE 21 is a bottom profile of an arrangement of knives yas shown in FIGURE 20,

FIGURE 22 is an end elevation of an alternative type of chip producing machine,

FIGURE 23 is a side elevation of another form of chip producing machine,

FIGURE 24 is an end elevation of another alternative form of chip producing machine,

FIGURE 25 is a partial side elevation of the machine shown in FIGURE 24,

FIGURE 26 is an end elevation of still another form of chip producing machine,

FIGURE 27 is a plan View of the m chi h i in FIGURE 26, and a ne s own FIGURE 28 is a side elevation of of chip producing machine.

of the chip shown still another form drum 2 has a hub 3 mounted on shaft 4 which is driven in any suitable manner. The shaft is journalled in bearings 5 mounted in a main frame 6. A plurality of spider arms '7 extend radially outwardly from the hub.

Each knife holder assembly comprises a holder suprings 10'in any suitable manner as by end lugs 9 supported by end rings 10 xedly mounted on the ends of the drum. Each support S has an outer arcute surface 11 and radially inwardly extending portions 12 and 13. The inner edge of portion 13 of each alternative support is seated on the outer edge of an arm '7.

A knife holder clamp 15 has one part 16 seated on the shoulders 17 each extending llaterally from a portion 13 of support 8. A second part 18 of clamp 15 has an outer arcuate surface 19 constituting va continuation of arcuate surface 11 of support 8. Part 18 has a shoulder 20 adjacent one end thereof supported on a complementary shoulder 21 on the adjacent edge of part 16. Part 18 has an inclined inner surface 22 in spaced parallel relation to an inclined surface 23 on part 16. The parts 16 and 1S are adapted to be clamped together by means of a plurality of Screws 24. A knife assembly 25 is arranged to be clamped between the inclined surfaces 22 and 23 of each clamp. Each knife assembly comprises a main knife 26 consisting of a rectangular blade having a sharpened cutting edge 27. A plurality of additional or front knife members or gouging tools 28 are mounted on knife 26. Each member 28 comprises a rectangular body portion 29 having one end edge sharpened as indicated at 30. Members 28 :are mounted on knife 26 with the inclined surfaces of their cutting edges in very slightly outwardly spaced relation (of the order `of 0.010 inch) with respect to the inclined surface of cutting edge 27 of knife 26. Cutting edges 30 are thus located in advance of cutting edge 27. Each member 23 is retained on knife 26 by suitable means such as Aa socket head screw 31 which extends through a slot 32 in member Z8.

Each member 28 has a pair of laterally extending Wings 33 each adjoining a respective end of cutting edge 30. Each wing 33 has a cutting edge 34 disposed angularly to cutting edges 27 and 30 and located in -a plane spaced outwardly from the plane of cutting edges 27 and 30.

The inclined surfaces Z3 of clamp holder part 1d has a plurality of complementary grooves 36 therein to receive the rearward portions of knife members 28. Surface 23 may also be provided with a plunality of reinforcing ribs 37 the inclined ends of which bear upon the members 28, as clearly shown in FIGURE 4. The inner edge of knife 26 is notched at 3S to receive the screws 24. It will be apparent that when the holder parts 16 and 13 are clamped together by means of screws 24, with the knife assembly therebetween, the latter will be securely clamped in the holder.

With each knife assembly clamped in the holder, and the holder seated in the drum, `as described, the cutting edges 27 and 30 and the leading ends of cutting edges 34 are disposed outwardly of the arcuate surface 19, a distance approximately equal to the desired thickness of the chip. However, this distance is desirably 0.001 to 0.500 inch and preferably 0.065 to 0.500 inch, As clearly shown in FIGURE 4, a chip-receiving spiace 39 is provided between each ladjacent pair of holders directly below the knife assembly. An anvil member 40 having an anvil 41 is mounted in each holder support S, the anvil 41 being disposed slightly forwardly of the cutting edges 30 and 34.

The distance between the cutting edges 34 on each knife member 28 and the space between each cutting edge 34 and the cutting edge 34 of the adjacent member 28 is dependent upon the desired width of chip. However, a satisfactory spacing between the cutting edges 34 on each member 28 is two and one-half inches with the members 28 spaced on four inch centers.

The length of each knife holder and knife assembly is approximately equal to the length of the logs from which the chips are to be produced.

Means for feeding logs onto the top of the revolving drum for engagement by the moving knife assemblies thereon comprises a feed hopper 42, the sides of which are constituted by a pair of travelling chains 43. Each chain 43 is carried by vertically aligned sprockets 44 mounted on shafts 45. Shafts 45 are supported in bearings 46 mounted in frame 47. The lower sprockets of each pair are driven by gears 48 in opposite directions. Thus, the

inner travelling por-tions of the chains move downwardly to feed logs 49 downwardly onto the drums. It will be observed that the logs 49 are disposed with their axes parallel to the axis of the drum.

A conical bale 53 on each end of the drum hub 3 directs chips from Ithe chip-receiving spaces 39 outwardly through the openings 54 in the ends of the drum, where they may be collected in any suitable manner.

In operation, with the drum revolving and the logs being fed onto the same -in the manner described, ini-tial Contact with the side surface of a log is by the cutting edges of the front knife members 28. It will be apparent that the cutting edges 34 will engage the log very slightly in advance of cutting edges 30. Actually, it has been determined .that in the structure described, cutting edges 34 will engage the log about 1&0 to 1/{100 of a second or less in advance of cutting edges 30 and thus, for practical purposes, the initial engagement of such cutting edges may be regarded as simultaneous. The cutting edges 34 may engage the log :approximately one-quarter to two inches in advance of cutting edges 30.

It will be apparent that the cutting edges 34 will produce grooves in the log surface extending angularly to the grain direction in the log. Preferably, each cutting edge 34 is ground in `a plane 50 lwhich is at an angle to the tangent of the log being cut. This angle, as shown, is of the order of 25. Thus, as it passes through the log, there is no end grain thrust against the wood left on the outside of the cutting edge. The wood on the inside of the cutting edges, i.e., the wood between the cutting edges 34 of each knife member 23, begins to be compressed, but since the relatively thin chip is simultaneously freed from the log in the grain direction by the cutting edge 30 (which is panallel to the log axis and the grain) the chip, as indicated at 51, is free to bend either parallel to the grain or has its tip twisted up by the knife member. As the chip bends parallel to the grain it fits into the channel between cutting edges 34. The included angle of this channel, between the bottom (the face of the member 28 between the cutting edges 34) and the sides (the opposite faces of the cutting edges 34), is substantially equal or greater than the angle between the parallel plane face of the chip and its end grain cuts. Thus, there can be little or no compression of thet wood in the chip.

While the knife member has been described as having a cutting edge 30, adapted to engage the wood parallel to the grain thereof, and cutting edges 34 in angular relation to cutting edge 30, it will be apparent that, in effect, only one continuous cutting edge is provided, portions of which are in angular relation to each other. It will further be observed that cutting edge 30 is at least twice the length of each cutting edge 34.

The angle of the cross gnain cutting edge 34, as represented by the plane Si) of the lower inclined surface of the knife member with the log surface in the longitudinal direction may be between 5 and 85 with a preferred range of 15 to 45, depending to some extent upon the thickness o-f the chip desired. Thus, the cut produced by the cutting edge 34 will be at an angle of 95 to 175 to the cut produced by cutting edge 30. (Moreover, the direction of the cut, as will be apparent from FGURE 3, is preferably substantially perpendicular to the gnain of the wood. However, it will be appreciated that, since logs are usually not quite straight, the angle of the direction of cut with the grain of the wood will frequently vary from the preferred It is desirable that the deviation from this preferred angle be not more than 20, and it is possible, from a practical point of view, to so restrict the treatment of logs in accordance with the invention. If the tangle of the direction of cut is more than 20 to the Wood grain, impairment of the fibers takes place with resulting lower pulp quality.

It will be apparent that the knife tools 2S will, in the production of chips thereby, leave a plurality of spaced grooves in the surface of the log with intervening land areas. These land tareas are engaged by the following cutting edge 27 of main knife 2e, such edge 27 also being disposed parallel to the gram direction in the wood. Cutting edge 27 will engage the land areas at approximately the base of cuts produced by cutting edges 34 and not lower since the plane of the cutting edge 27 is very slightly lower than the plane of cutting edges 34, i.e., to a degree suflicient to ensure ya clean cut between the edges of each land area. it will be observed that such edges are parallel and since no endwise compression is imposed thereon, no endwise or cross grain compression is exerted on the resulting chip produced as indicated at 52.

1n the production of chips as described, any endwise compression exerted on the chip during its formation is believed lto be not substantially greater than 0.060 inch per inch of free chip length and preferably not greater than 0.010 to 0.040 inch per inch of free chip length.

The chip 51 produced is shown in FIGURES 8, 9 and 10. It has two substantially parallel major faces 55 which may be approximately 0.001 'to 0.500 inch or more apart 'and preferably 0.065 to 0.500 inch apart; two faces 56 broken randomly with the grain direction (one or both Iof these faces might be the outer surface of the log), and two other regular faces 57, the four corners of which are generally straight and parallel. As shown, each face 57 is inclined at an angle of approximately 25 to a face 55. Having regard to the angular relationship of the cutting edges 30 and 34, as previously set forth, the face 57 is inclined at an angle of 85 to 5 to a face 55. It will also be apparent that the general description of chip 52 will be the same as that of chip 51. The faces of chip 52 corresponding to the faces 57 of chip 51 will, however, be disposed at substantially right angles to the major faces thereof. Thus, the chip produced has four corners 58 and 59 which are parallel to each other zand four corners 60 and 61 which lare random with the grain. Thus, the Wood of the logs has been subdivided into chip form regular in two dimensions without altering the pulping characteristics 5f the wood.

Sulphite pulp prepared from chips produced in accordmce with the invention has much superior qualities as compared with sulphite pulp prepared from chips produced by presently available commercial chippers. The following tables give the results of comparison tests, column numbered (l) being values relating to regular pulp prepared from chips produced in conventional commercial manner and column numbered (2) being values relating to pulp prepared from chips produced in accordance with the present invention.

A. Bleached Sulphite Pulps Beater Evaluation:

Properties at 300 C.S. Freeness- Burst Factor- 5l 67 Tear Factor .67 72 Breaking Leng (meters) 8, 460 10, 200 Dynamic Breaking Stress (em. 1.6 2.0 Statie Breaking Stress (kg.) 7. 7 8. 8 Stretch (mm.) 2. 9 3. 4 Bulk (cc./g.) 1.29 1.28 Beating Time (min.) 54 40 Fiber Length Classification, Percent Retained 14 mesh 4. 5 11.2 30 mesh 31.6 40. 3 100 mesh 29. 9 24. 8 Percent Fines (pass 100 mesh) 34.0 23. 7 Ball Mill Evaluation:

Properties at 300 C.S. Freeness- Burst factor 48 58 Breaking Length (meters) 9, 000 Fold (M.I.T.) 1,000 Beating Time (min.) 144 144 Fiber Length Classification, Percent Retained on 14 mesh 21.1 34. 3 Percent Fines (Pass 1GO mesh) 22. 6 G. 5

5 Properties at 300 C.S. Freeness:

E B. Unbleached Sulphz'te Pulps Heater Pulp Test- Burst factor Tensile-Breaking length Impact Tensile Porosity (relative) Double folds No. 14 mesh) Resistance to Mechanical Damage- Percent long bers (retained on N o. 14 mesh) in untreated pulp. Percent long fibers (retained on No. 14 mesh) in pulp treated Waring Blender Resistance to Acid Hydrolysis- Percent long' fibers (retained on N o. 14 mesh) after hydrolysis in 0.25 N. sulphurie at 100 C 19 33 Same as above after treatment in "Varing Blender 2 4 Percent long nbers retained in N o. 30 mesh in above pulp after treatment in Waring Blender.

lt wili be apparent that various other arrangements of knives may be provided to produce chips in accordance with the invention. A number of such alternative arrangements wiil now be described.

Referring to FGURES 11 and 12, 62 is a portion of a drum corresponding to drum 2. A knife holder 63 is mounted in the drum and carries a plurality of pairs of circumferentially aligned slitter knives or gouging tools 64 having cutting edges 65 spaced apart the width of chip desired. A second knife holder 66 rearwardly of holder 63 .comprises a pair of clamping parts 67 and 68 with connecting screws 69 and between which is clamped a knife 70 having a cutting edge 71. it will be understood that cutting edges 65 correspond to cutting edges 34 of the first modification, and cutting edge 71 coresponds A to cutting edge 27 thereof. It will also be understood that a plurality of successive holders 63 and 66 and knife assemblies will be provided in the drum 62. A chip receiving space 72 is provided between the knife holders.

The modication shown in FIGURE 13 is quite similar to that shown in FIGURES l1 and 12 with the exception that instead of slitter knives 64, a disc '73 with cutting edge 74 is rotatably mounted in a holder 75.

it will be apparent that, in each of the two modifications just described, the slitter knives or tools 64 or disc 73 will initiate the formation of slits in the log surface angularly to the grain of the Wood and that immediately after such initiation, the knife 70 will engage the slitted wood area to produce chips.

Referring to FIGURES 14 and 15, a knife assembly '75 is therein illustrated which may be employed as au alternative to that illustrated in FIGURES l to 4. Assembly 76 includes clamping parts 77 and 7S corresponding to parts 116 and 18 as well as a series of knife members or tools '79 similar to knife members 2S. However, instead of the main knife 26, a second series of knife members '79 is mounted between the clamps, the members of such second series being disposed opposite the spaces between the members of the first series. By particular reference to FIGURE 15, it will be apparent that the irst series of members '79 will produce chips while leaving land areas between the resulting gouges in the log face, and that the second series of members 79 will remove such gouges also to provide chips.

FIGURES 16 and 17 illustrate a knife member 80 which may be employed alternatively to knife members 28 or 79. Member S0 has a main cutting edge 81 and a pair or" cutting edges 82 extending angularly to cutting edge 81. However, each cutting edge 52 has a curved inner face 83 instead of the Hat plane 50 of the inner face of cutting edge 34. FIGURE 17 illustrates diagrammaticaily a manner of mounting two series of knife members in a manner similar to the modirication of FIG- URES 14 and 15.

FIGURES 18 and 19 illustrate still another knife member or tool 84 which may be employed alternatively to knife members 28 or 79. Member tid has a main cutting edge S comprising two straight sections 56 obliquely inclined with respect to each other, as well as a pair of cutting edges S7 constituting the end portions of cutting edge 35. It will be apparent that the chip produced by such a knife member will be of flattened triangular cross-section. FIGURE 19 shows diagrammatically a suitable arrangement of two series of such members 84.

FIGURES 20 and 21 show a modified knife member or tool 88 having a main cutting edge S9 and a single cutting edge 911 extending angularly thereto. It will be observed that, with knife members 83 arranged in slightiy overlapping series as shown in FGURE 21, the cutting edges 90 of adjacent knife members will perform the cross grain slits in the log surface and the intervening cutting edge 89 of one member 83 will perform the slabbing operation.

It will also be understood that various alternative forms of chip producing machines in accordance with the invention may be provided.

FIGURE 22 illustrates one such modified form of machine wherein a plate 91 is mounted for up and down oscillating movement in guides 92 by means of a pitman 93 and driving wheel 94. Plate 91 carries a series of spaced slitter knives or gouging toois 95 in advance of a main knife 96 with a chip-receiving space 97 therebetween. Means for feeding logs to this guillotine type of knife assembly comprises upper and lower feed chains 98 and 99 and a feed hopper 190. It will be apparent that the machine may be arranged to provide a direction of movement of the knife-carrying plate in a horizontal or angular direction instead of the vertical direction illustrated.

FIGURE 23 illustrates another form of chipper which includes a travelling chain 1111 mounted on sprocket 192, and drive sprocket 163, the chain having upper and lower horizontal travelling portions. The chain carries a plurality of knife assemblies 1114 each comprising a knife holder 105, and a series of slitter knives or grooving tools 1% and a main knife 107 mounted in the holder with an intervening chip-receiving space 193. Means for feeding logs onto the upper travelling portion of the chain for engagement by the knives comprises a magazine 1119. A chip conveyor 11i) may be arranged below the magazine between the upper and lower travelling portions of the chain.

FIGURES 24 and 25 illustrate still another form of chipper which comprises a plurality of axially arranged drive rings 111 interconnected by frame members 112 and 113. The drive rings are mounted on trunnions 114, one or more of which are driven to impart rotative movement to the drive ring assembly. Mounted in each axially extending frame member 112 is a knife assembly 115, which may be similar to knife assembly but with knives 116 and 117 (corresponding to knife 26 and knife members Z8) directed inwardly of the rings. Means for feeding logs against the inner surface of the rings for engagement by the knives comprises a baflie 11S between which and the inner surface of the rings logs may be fed and a driven roll 119 having a portion of its periphery constituting a continuation of the baie. The roll 119 has a serrated or grooved surface 12b for frictional engagement with the logs.

FIGURES 26 and 27 illustrate still another form of chipper which includes a horizontally disposed disc 121 rotatably driven by means of a shaft 122. Mounted on the disc are a plurality of knife assemblies 123 each cornprising a series of slitter knives 124 and a main or slabbing knive 125 with intervening chip-receiving space 126. It will be apparent that any of the previously described slitting knives or gouging tools may be employed instead of the slitter knives 124. Means for feeding logs onto the upper horizontal surface of the revolving disc for engage- CAB 8 ment by the knife assemblies 123 comprises a feed chute 127 and feed chains 12?.

Referring to FIGURE 28, 131 is a drum mounted for rotation on driven shaft 132 in the direction indicated. A plurality of knife or tool assemblies 133 are mounted on the drum each comprising a series of slitter knives or gouging tools 1de and a main knife 135 with intervening chip-receiving space 136. Means for feeding logs against the lower downwardly travelling portion of the drum for engagement by the knife assemblies comprises, as shown, a feed chain 137. A retaining arm 138 may be provided above the supply of logs on the chain.

it will be observed that, in each of the modifications, the leading end of each slitting or cross grain cutting knife or gouging tooi is located very slightly in advance of the cutting edge of the slabbing or parallel grain cutting knife. Generally speaking, such leading end will not be more than two inches in advance of the slabbing knife cutting edge.

The ground cutting edge surfaces of the slabbing knives, such as indicated at 129 in respect of knife 26 and at 130 in respect of cutting edge 3Q of knife member 2S may be sharpened at any satisfactory angle. A satisfactory angle is approximately 40 from the lower face of the blade as shown. Moreover the angle at which the knives wiil be mounted in the respective holders will be chosen to meet varying conditions. In respect of knife 26 and knife members 2S, the blades thereof are disposed in the hoiders at an angle of approximately 40, which has been found to be satisfactory.

it will be understood that various types and forms of log feeding means, other than those illustrated, may be employed in any of the modifications described.

in respect of a tool such as 28, it will be understood that the leading end of each cutting edge 34 may be. disposed slightly rearwardly, slightly forwardly, or coincident with cutting edge 30. In the tool illustrated, it is slightly forwardly of such cutting edge 311.

We claim:

1. A method of producing wood chips for pulping which comprises cutting the surface area of a log in a direction deviating less than 20 from a direction perpendicular to the grain of the wood of said log and along a line of coincidental log engagement having a major portion extending generally parallel to said wood grain and simultaneously cutting a minor portion extending angularly to said wood grain.

2. A method of producing chips as defined in claim 1 wherein said line of log engagement is continuous from end to end thereof.

3. A method for producing chips as defined in claim 1, each of said end portions of said line of log engagement being at an angle of to 175 to said intermediate portion of said cut.

4. A method of producing wood chips for pulping which comprises cutting the surface area of a log in a direction deviating less than 20 from a direction perpendicular to the grain of the wood of said log and along a line of coincidental log engagement having a major intermediate portion extending generally parallel to said wood grain and simultaneously cutting minor end portions each extending angularly to said wood grain, said intermediate portion being at least twice the length of each of said end portions.

5. A method of producing wood chips for pulping which comprises, effecting simultaneously a plurality of spaced aligned log cutting steps each comprising cutting the surface area of a log in a direction deviatng less than 20 from a direction perpendicular to the grain of the wood of said log and along a line of coincidental log engagement having a maior intermediate portion extending generally parailel to said wood grain and simultaneously cutting minor end portions each extending from an end of said major portion and angularly to said wood grain, said intermediate portion being at least twice 3,155,130 9 i@ the length of each of said end portions, said log cutting References Cited bythe Examiner steps producing chips from said 10g Isurface area and UNITED STATES PATENTS forming a plurality of grooves therein, and thereafter 1776180 9/30 Cobb 144 218 X cutting from said surface area the land sections between 8763311 3/59 MatthgVQg-:n 144 162 said grooves thereby produolng additional ch1ps. LEON PEAR, Primary Examiner. 

1. A METHOD OF PRODUCING WOOD CHIPS FOR PULPING WHICH COMPRISES CUTTING THE SURFACE AREA OF A LOG IN A DIRECTION DEVIATING LESS THAN 20* FROM A DIRECTION PERPENDICULAR TO THE GRAIN OF THE WOOD OF SAID LOG AND ALONG A LINE OF COINCIDENTAL LOG ENGAGEMENT HAVING A MAJOR PORTION EXTENDING GENERALLY PARALLEL TO SAID WOOD GRAIN AND SIMULTANEOUSLY CUTTING A MINOR PORTION EXTENDING ANGULARLY TO SAID WOOD GRAIN. 